Usb endpoint – Freescale Semiconductor MCF5480 User Manual
Page 920
MCF548x Reference Manual, Rev. 3
29-46
Freescale Semiconductor
29.2.5.11 USB Endpoint n Last Read Frame Pointer (EPnLRFP)
Table 29-45. EPnFWP Field Descriptions
Bits
Name
Description
31–12
—
Reserved, should be cleared.
11–0
WP
Write pointer. This value is maintained by the FIFO hardware and is not normally written.
Writing to these bits will disrupt the integrity of the data flow. This value represents the
Write address being presented to the FIFO RAM.
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
Uninitialized
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R
0
0
0
0
LRFP
W
Reset
Uninitialized
0
0
0
0
0
0
0
0
0
0
0
0
Reg
Addr
MBAR + 0xB468 (EP0LRFP); 0xB498 (EP1LRFP); 0xB4C8 (EP2LRFP);
0xB4F8 (EP3LRFP); 0xB528 (EP4LRFP); 0xB558 (EP5LRFP); 0xB588 (EP6LRFP)
Figure 29-51. USB Endpoint n Last Read Frame Pointer (EPnLRFP)
Table 29-46. EPnLRFP Field Descriptions
Bits
Name
Description
31–12
—
Reserved, should be cleared.
11–0
LRFP
Last read frame pointer. FIFO-maintained pointer that indicates the start of the most
recently read frame or the start of the frame currently in transmission. The LRFP can be
read and written for debug purposes. For the frame retransmit function, the LRFP indicates
which point to begin retransmission of the data frame. There are no safeguards to prevent
retransmitting data that has been overwritten. When EPnFCR[FRM] is not set, this pointer
has no meaning.